Plant isoflavone and isoflavanone O-methyltransferase genes

Abstract

The invention provides enzymes that encode O-methyltransferases (OMTs) from Medicago truncatula that allow modification to plant (iso)flavonoid biosynthetic pathways. In certain aspects of the invention, the genes encoding these enzymes are provided. The invention therefore allows the modification of plants for isoflavonoid content. Transgenic plants comprising such enzymes are also provided, as well as methods for improving disease resistance in plants. Methods for producing food and nutraceuticals, and the resulting compositions, are also provided.

What is claimed is: 
     
       1. An isolated nucleic acid sequence selected from the group consisting of:
 (a) a nucleic acid sequence encoding the polypeptide of SEQ ID NO:9; 
 (b) a nucleic acid sequence comprising the sequence of SEQ ID NO:2; 
 (c) a nucleic acid sequence encoding a plant isoflavonoid O-methyltransferase that hybridizes to the full-length complementary sequence of SEQ ID NO:2 under conditions of 0.15 M NaCl and 70° C.; and 
 (d) a nucleic acid sequence encoding a plant isoflavonoid O-methyltransferase, wherein the nucleic acid sequence has at least 90% sequence identity to the nucleic acid sequence of SEQ ID NO:2, wherein the isolated nucleic acid sequence is operably linked to a heterologous promoter. 
 
     
     
       2. A recombinant vector comprising a nucleic acid sequence operably linked to a heterologous promoter, wherein the nucleic acid sequence is selected from the group consisting of:
 (a) a nucleic acid sequence encoding the polypeptide of SEQ ID NO:9; 
 (b) a nucleic acid sequence comprising the sequence of SEQ ID NO:2; 
 (c) a nucleic acid sequence encoding a plant isoflavonoid O-methyltransferase that hybridizes to the full-length complementary sequence of SEQ ID NO:2 under conditions of 0.15 M NaCl and 70° C.; and 
 (d) a nucleic acid sequence encoding a plant isoflavonoid O-methyltransferase, wherein the nucleic acid sequence has at least 90% sequence identity to the nucleic acid sequence of SEQ ID NO:2. 
 
     
     
       3. The recombinant vector of  claim 2 , further comprising at least one additional sequence chosen from the group consisting of: a regulatory sequence, a selectable marker, a leader sequence and a terminator. 
     
     
       4. The recombinant vector of  claim 3 , wherein the additional sequence is a heterologous sequence. 
     
     
       5. The recombinant vector of  claim 3 , wherein the promoter is a developmentally-regulated, organelle-specific, inducible, tissue-specific, constitutive, cell-specific, seed-specific, or germination-specific promoter. 
     
     
       6. The recombinant vector of  claim 3 , defined as an isolated expression cassette. 
     
     
       7. A transgenic plant transformed with the recombinant vector of  claim 2 . 
     
     
       8. The transgenic plant of  claim 7 , further defined as a monocotyledonous plant. 
     
     
       9. The transgenic plant of  claim 7 , further defined as a dicotyledonous plant. 
     
     
       10. The transgenic plant of  claim 9 , further defined as a legume. 
     
     
       11. The transgenic plant of  claim 7 , further defined as an R 0  transgenic plant. 
     
     
       12. The transgenic plant of  claim 7 , further defined as a progeny plant of any generation of an R 0  transgenic plant, wherein said progeny plant has inherited said recombinant vector from said R 0  transgenic plant. 
     
     
       13. A plant part of the plant of  claim 7 , wherein said plant part comprises the recombinant vector. 
     
     
       14. A seed of the transgenic plant of  claim 7 , wherein said seed comprises said recombinant vector. 
     
     
       15. A host cell transformed with the recombinant vector of  claim 2 . 
     
     
       16. The host cell of  claim 15 , wherein said host cell is a plant cell. 
     
     
       17. A method of increasing flavonoid biosynthesis in a plant, comprising introducing into said plant the recombinant vector of  claim 2 , wherein the nucleic acid sequence encoding isoflavonoid O-[ ]methyltransferase is expressed to increase flavonoid biosynthesis in the plant grown under stress conditions relative to a plant of the same genotype lacking the recombinant vector and grown under said stress conditions. 
     
     
       18. The method of  claim 17 , wherein the recombinant vector is inherited from a parent plant of said plant. 
     
     
       19. The method of  claim 18 , wherein the plant is an R 0  plant transformed with the recombinant vector.